The main frame of a telephone central office contains electrical junctions between pairs leading to customer loops on the outside plant and to switching or other equipment within the central office. Many central offices also have termination frames to which certain equipments such as Metallic Facility Terminals are connected by wire pairs.
All central office wire frames are constantly being physically rearranged to accommodate new and changing loop and central office equipment requirements. Additionally, any surge in telephone loop for a given central office occasions a corresponding increase in wire frame connections and rearrangements. As a result of these factors, many central offices have become pressed for space to expand; and existing space utilization has come under increased scrutiny.
It has come to be recognized that state-of-the-art main frame connecting blocks, first of all, do not afford a high enough electrical connection density. Further, these blocks do not afford a sufficient degree of protection of the wires from physical damage during the constant rearrangement process described. Then, too, existing blocks do not adequately organize the individual wires, making main frame activity time-consuming and on occasion, uncertain.
An important element of organization -- accessibility of the wires from both sides of the connection -- also is lacking in existing connecting blocks. Also, many block designs are susceptible to "hits", or unintentional electrical bridging by an installer's tool as he works on given terminals.
The congestion, exposure, and difficulty of rearrangement, which generally characterize state-of-the-art wire frame connecting blocks, pose a multifaceted problem, a solution of which is afforded by the present invention.